A method for hermetic encapsulation of a component is, for example, known from WO 99/43084. There components, in particular surface wave components, are applied in a flip-chip technique to a substrate provided with solderable connection areas. The component, which is fashioned on the chip, is thereby soldered to the substrate over bumps (solder balls) at a slight distance from the substrate, such that the component structures located on the chip face the substrate. For hermetic encapsulation of the components located on the substrate, said components are ultimately covered from the back with a metal foil or a metal-coated plastic film (first metal layer) on the substrate and glued or laminated. The foil thereby seals tight with the substrate between the components, such that an encapsulation is created for the component structures.
After the application of the electrical component on the substrate, the lower edge of the chip and regions of the substrate abutting the chip are frequently covered with a material (under filler), for example organosilic compound or epoxy resin filled with quartz, on which the first metal layer mentioned above is subsequently applied. In another embodiment, for example, a plastic film is applied on the back side of the component chip and regions of the substrate abutting the component, and the film is subsequently sealed with the substrate. The first metal layer is subsequently applied on this film.
In order to tightly encapsulate the component, a second metal layer is normally deposited galvanically or, respectively, without current on this first metal layer. During this galvanic process, small quantities of water can penetrate into the electrical component. This water can lead to long-term corrosion of the electrical component. Until now, after the galvanic reinforcement of the first metal layer, this moisture has only been homogenously distributed in the component via a tempering step at a typical temperature of 125° C., without completely removing the moisture from said component.